<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            padding: 0px;
            margin: 0px;
            list-style: none;
            box-sizing: border-box;
            text-decoration: none;
        }

        .ul {
            display: flex;
            flex-wrap: wrap;
            width: 1200px;
            margin: auto;
        }

        .ul>li {
            width: 33.33%;
            height: 100px;
            background-color: yellow;
            border: 1px solid #000;
        }

        .box2 {
            width: 1200px;
            margin: auto;
            display: flex;
            align-items: center;
            justify-content: center;
        }

        .box2>div {
            
            background-color: yellow;
            border: 1px solid #000;
        }

        .div-left {
            height: 100px;
            width: 25%;
        }

        .div-center {
            height: 200px;
            width: 25%;
        }

        .div-right {
            height: 300px;
            width: 50%;
        }

    </style>
</head>

<body>
    <ul class="ul">
        <li>1</li>
        <li>2</li>
        <li>3</li>
        <li>4</li>
        <li>5</li>
        <li>6</li>
        <li>7</li>
        <li>8</li>
        <li>9</li>
    </ul>

    <div class="box2">
        <div class="div-left">1</div>
        <div class="div-center">2</div>
    </div>
</body>

</html>